Various compositions are known to be useful as treating agents to provide surface effects to substrates. Surface effects include repellency to moisture, soil, and stains, and other effects, which are particularly useful for fibrous substrates such as fibers, fabrics, textiles, carpets, paper, leather, and other such substrates. Many such treating agents are fluorinated polymers or copolymers.
Fluorinated polymer compositions having utility as fibrous substrate treating agents generally contain pendant perfluoroalkyl groups of three or more carbon atoms, which provide oil- and water-repellency when the compositions are applied to fibrous substrate surfaces. The perfluoroalkyl groups are generally attached by various connecting groups to polymerizable groups not containing fluorine. The resulting monomer is then generally copolymerized with other monomers, which confer additional favorable properties to the substrates. Various specialized monomers may be incorporated to impart improved cross-linking, latex stability and substantivity. Since each ingredient may impart some potentially undesirable properties in addition to its desirable ones, the specific combination is directed to the desired use. These polymers are generally marketed as aqueous emulsions for easy application to the fibrous substrates. U.S. Pat. No. 6,479,605 discloses a fluorinated copolymer useful for treating fibrous substrates to provide oil repellency and water repellency.
Various attempts have been made to increase the oil- and water-repellency imparted to the substrate and its durability while reducing the amount of fluorinated polymer required, i.e., boost the efficiency or performance of the treating agent. One method is to incorporate blocked isocyanates or melamine resins. However, only limited amounts can be used because these ingredients tend to adversely affect the handle (the feel) of the fibrous substrates. Another method is the use of various extender polymers. These are typically hydrocarbon polymers in aqueous emulsions, which are blended with the fluorinated polymer emulsion before application to the substrate.
U.S. Pat. No. 6,309,752 discloses compositions comprising a fluorochemical agent, a copolymer extender comprising two distinct polymerized units, and a blocked isocyanate extender, wherein the extenders in combination improve the fluorine efficiency of the fluorochemical agent to a greater degree than either of the extenders alone. The two distinct polymerized units are (1) optionally halogenated polymerizable ethylenic compounds, particularly acrylates; and (2) ethylenic compounds containing a functional group that can react with a fabric. It has been found that blocked isocyanate extenders tend to adversely affect the hand (feel) of the fibrous substrate.
There is a need for polymer compositions, which significantly improve the performance of surface effect agents. In particular, there is a need for compositions which improve the performance of fluorinated polymer treating agents for substrates to provide repellency and other surface effects while reducing the amount of fluorinated polymer required. The present invention provides such a composition.